1. Field of the Invention
The present invention relates to a heater particularly effective if it is used in a fixing apparatus of an image forming apparatus such as a copier or printer, and to an image heating apparatus using this heater.
2. Related Background Art
For conveniencexe2x80x99 sake, an image heating fixing apparatus as an example of a heating apparatus will be described.
In an image forming apparatus such as a copier, printer, or facsimile, an image heating fixing apparatus is a heating apparatus for heating/fixing-processing, on a recording material surface, an unfixed toner image corresponding to image information formed on the surface of a recording material (electro fax sheet, electrostatic recording sheet, transferring material sheet, print paper, or the like) in a direct or indirect (transferring) system using toner made of a thermomeltable resin or the like by proper image forming process means such as electrophotography, electrostatic recording, magnetic recording, or the like.
Conventionally, for such an image heating fixing apparatus, a heat roller system has been widely used. The heat roller system is a system which has a basic construction comprising a metallic roller provided therein with a heater, and a pressure roller having an elasticity and pressure-contacted to said roller, and in which, by passing a recording material through a fixing nip portion formed by one pair of these rollers, an unfixed toner image bore on said recording material is heated and pressurized to fix.
However, in the above heat roller system, since the heat capacity of the roller is large, very much time was required for raising the roller surface to a desired fixing temperature. Besides, for this reason, for quickly executing an image output operation, there is a problem wherein the roller surface must be temperature-adjusted to a temperature in a certain extent even when a machine is not used.
One improved and devised on that point is disclosed in Japanese Patent Application Laid-open No. 10-293490. This is composed by an insulating layer and a heat generation layer are laminated on a surface of a metallic roller. Such a roller is difficult in manufacture, besides, since a contact point for supplying an electric power to the roller slides, problems such as generation of noise and a short duration arise, so it does not reach a practical use in practice.
So, the present applicant has proposed before a heating apparatus of a film heating system (for example, see Japanese Patent Application Laid-open No. 63-313182, Japanese Patent Application Laid-open No. 2-157878, Japanese Patent Application Laid-open No. 4-44075, and Japanese Patent Application Laid-open No. 4-204980.
This film heating system is a system in which a heating body and a heated material are put into close contact with one surface side and the other surface side of a heat-resisting film, respectively, and the thermal energy of the heating body is given to the heated material through the heat-resisting film, and a heating apparatus of an on-demand type in which members of low heat capacity can be used for the heating body and film, there is quick startability, and the power consumption in standby is considerably small, can be constructed.
FIGS. 12A to 12C show one example of a heating apparatus of the film heating system. This example is an image heating fixing apparatus of the film heating system. FIG. 12A is an enlarged cross-section model view of a principal part, FIG. 12B is a partially cut-off plan model view on the surface side of a heating body, and FIG. 12C is a plan model view on the back surface side of the heating body.
Reference numeral 7 denotes a heating body, which is a slender and thin-plate-shaped member whose longitude is a vertical direction to the drawing surface of FIG. 12A, entirely low heat capacitive, and generates heat by being electrified.
Reference numeral 13 denotes a heating body support member, whose longitude corresponds to a vertical direction to a drawing surface of FIG. 12A, being adiabatic and rigid. On the lower surface side of this support member 13, along the member longitude, a seat gouged portion 13a elongating in the longitudinal axis and in shallow grooved shape into which the above heating body 7 can be fitted is comprised, and the heating body 7 is fitted into this seat gouged portion 13a and supported by the support member 13.
Reference numeral 12 denotes a thin heat-resisting film and 9 does an elastic pressure roller, the film is sandwiched, and the heating body 7 supported by the support member 13 and the pressure roller 9 are pressure contacted with a predetermined pressure force to form a fixing nip portion (heating nip portion) N.
The film 12 moves in an arrow direction with close contacting the fixing nip portion N to the surface on the downward facing side of the heating body 7 and sliding by a not-shown drive member, or the pressure roller 9 being rotation-driven.
And, when a paper leaf body (recording material) 11 carrying an unfixed toner image 10, as a heated material, is introduced between the film 12 of the above fixing nip portion N and the pressure roller 9, the paper leaf body 11 is sandwich-conveyed in the fixing nip portion N together with the film 12 and heated by heat from the heating body 7 through the film 12, and unfixed toner 10 is heat-fixed on the paper leaf body surface. The paper leaf body 11 passed through the fixing nip portion N is separated from the surface of the film 12 and conveyed.
As the heating body 7, a so-called ceramic heater in which a ceramic board having electrical-insulating performance, good heat conductivity and heat-resistivity is used as a heating body board. The heating body 7 of this example is a ceramic heater.
That is, 1 denotes a slender and thin-plate-shaped ceramic board.
Reference numeral 2 denotes first and second parallel two-stripe narrow-band-shape electrification heat-generation resistor patterns (one is a first, the other is a second) formed and comprised along the board longitude on the surface side of this ceramic board 1.
Reference numeral 5 denotes two conductor patterns (one is a first, the other is a second) as the first and second power supply electrodes (electrode contact points) formed and comprised with being arranged on the longitude one end portion side of the ceramic board surface. The first power supply electrode 5 is electrically conducted to one end portion of the first resistor pattern 2 through an extension pattern portion. Besides, the second power supply electrode 5 is electrically conducted to one end portion of the second resistor pattern 2 through an extension pattern portion.
Reference numeral 6 denotes a conductor pattern as a folded-back electrode formed and comprised on the ceramic board surface by electrically conducting between the other end portions of the first and second resistor patterns 2.
Reference numeral 3 denotes a heater surface protective glass layer, which is formed and comprised to cover substantially entirely the heater surface except the portion of the first and second power supply electrodes 5. By this protective glass layer 3, each extension pattern portion of the first and second resistor patterns 2 and the first and second power supply electrodes 5, and the folded-back electrode 6 are protected by being covered.
Reference numeral 4 denotes a temperature sensing element such as a thermistor or the like, which is disposed by being contacted to substantially the center portion in the longitudinal direction on the heater back surface side, that is, the back surface side of the ceramic board 1.
The surface side having the protective glass layer 3 of the above ceramic heater 7 is the film sliding surface side, and the surface side of this ceramic heater 7 is exposed to the exterior and fitted in the seat gouged portion 13a on the lower surface side of said support member 13 and disposed.
Reference numeral 8 denotes a power supply connecter. By predetermined fitness to the power supply connecter mounting portion of the support member 13 disposing and supporting the heater 7, first and second power supply spring contact points 8a on the power supply connecter 8 side are pressurized and contacted to the first and second power supply electrodes 5 of the heater 7, and the heater 7 and a not-shown power supply circuit are electrically connected.
By performing power supply from the power supply circuit through the power supply connecter 8 to the first and second power supply electrodes 5, by the electrification heat-generation resistor patterns 2 generating heat throughout the longitude entire length, the heater 7 rapidly raises the temperature. And, the temperature rising information is converted into voltage information by the temperature sensing element 7 disposed on the heater back surface side and detected, the output is calculated by a not-shown control circuit such as CPU or the like, and an AC input from the power supply circuit to the heater 7 is adjusted so that the temperature of the heater 7 is temperature-controlled to a predetermined temperature.
In the fixing apparatus adopting such a film heating system, since the film 12 of a low heat capacity and the heater 7 can be used, it becomes possible to shorten a wait time (quick start) as compared with the conventional heat roller system. Besides, since the quick start can be done, pre-heating upon non-print operation becomes unnecessary, and power-saving in a synthetic meaning can be intended.
By the way, as the ceramic heater of the above-described example, the heating body using the ceramic board such as alumina as the board has the problems that the ceramic is fragile, or, the cost is high, it is unsuitable for bending processing or the like, and the like.
So, in Japanese Patent Application Laid-open No. 9-244442, Japanese Patent Application Laid-open No. 10-275671, a heating body (hereinafter, referred to as conductive board heater) in which, by forming an insulating layer on a metal, a board having the same insulation ability as the conventional ceramic board is made, and a resistor pattern, a conductor pattern, and an insulating sliding layer of the uppermost layer are formed thereon is proposed.
However, in the conductive board heater using metal as the board, since thermal expansion is large, and expansion and shrinkage are repeated in a heating apparatus, there is a defect that the electrode portion to which the power supply spring contact point on the power supply connecter side is pressurized and contacted is worn and contact inferior occurs and it is easy to break.
Besides, since the position of the resistor pattern of the heating body varies, excessive heating, insufficient heating, uneven heating at an end portion, or uneven curl unevenness at a paper end is occurred.
The present invention has been made in view of the above problems, and its object is to a heater that can prevent contact defect between an electrode provided in the heater and a connecter of an image heating apparatus holding this heater, and an image heating apparatus using this heater.
Another object of the present invention is to provide a heater that can prevent heating defect by thermal expansion of the heater, and an image heating apparatus using this heater.
Still another object of the present invention is to provide an image heating apparatus having:
a heating member for heating an image on a recording material, the heating member having a metallic substrate and heat generating resistor;
a supporting member for supporting the heating member;
wherein the metallic substrate having a positioning portion for positioning the metallic substrate on the supporting member.
Still another object of the present invention is to provide a heater having:
a metallic substrate;
a heat generating resistor;
wherein the metallic substrate having a positioning portion for positioning the metallic substrate on the image heating apparatus.
Still another object of the present invention is to provide a heater having:
a substrate, the substrate having a positioning portion for positioning the substrate on the image heating apparatus;
a heat generating resistor;
wherein the positioning portion is provided in the interior of the substrate.
Further objects of the present invention will become apparent by reading the below detailed description with reference to the accompanying drawings.